Semiconductor Device and Method

ABSTRACT

A vertical gate all around (VGAA) is provided. In embodiments, the VGAA has a nanowire with a first contact pad and a second contact pad. A gate electrode is utilized to help define a channel region within the nanowire. In additional embodiments multiple nanowires, multiple bottom contacts, multiple top contacts, and multiple gate contacts are utilized.

BACKGROUND

As the semiconductor industry has progressed into nanometer technologynodes in pursuit of higher device density, higher performance, and lowercosts, challenges from both fabrication and design issues have resultedin the development of three-dimensional designs, such as a vertical gateall around (VGAA) transistor. A typical GAA transistor enables enhancedcontrol of the charge carriers along the lengthwise direction through acomplete encirclement of the channel region of a semiconductor nanowireby a gate dielectric and a gate electrode. The GAA transistor has areduced short channel effect, because the channel region may besurrounded by the gate electrode so that an effect of the source/drainregion on an electric field of the channel region may be reduced.

However, there are challenges to implementation of a VGAA. For example,the processes and methods utilized in complementarymetal-oxide-semiconductor (CMOS) fabrication are not specificallytailored for the manufacture of VGAA transistors. As such, improvementsare needed in the manufacturing processes in order to manufacture VGAAtransistors.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIGS. 1A-1C illustrate a vertical gate all around transistor inaccordance with some embodiments.

FIGS. 2A-3D illustrate embodiments that utilize multiple nanowires inaccordance with some embodiments.

FIGS. 4-5 illustrate embodiments that utilize an array of nanowires inaccordance with some embodiments.

FIGS. 6A-6F illustrate embodiments that utilize one or more bottomcontacts in accordance with some embodiments.

FIGS. 7A-7E illustrate embodiments that utilize one or more top contactsin accordance with some embodiments.

FIGS. 8A-8C illustrate embodiments that utilize a single top contact inaccordance with some embodiments.

FIGS. 9A-9F illustrate embodiments that utilize one or more gatecontacts in accordance with some embodiments.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

With reference now to FIGS. 1A-1C (with FIG. 1B being a cross-sectionalview of FIG. 1A through line B-B′ and FIG. 1C being a cross-sectionalview of FIG. 1A through line C-C′), there is illustrated a vertical gateall around (VGAA) transistor 100 with a substrate 101 with a firstnanowire 111, a first contact pad 103, a gate dielectric 102, a gateelectrode 105, a second contact pad 113, a first bottom contact 109, afirst top contact 115, and a first gate contact 107. In an embodimentthe substrate 101 comprises a semiconductor substrate (e.g., Si, SiGe,or SiGeB). In alternative embodiments, the substrate 101 comprises asilicon-on-insulator (SOI) structure. In some embodiments, the substrate101 may comprise a compound semiconductor including silicon carbide,gallium arsenide, gallium phosphide, indium phosphide, indium arsenide,and indium antimonide; an alloy semiconductor including SiGe, SiGeSn,GeSn, GaAsP, AlInAs, AlGaAs, GaInAs, GaInP, and GaInAsP; or combinationsthereof.

In some embodiments, the substrate 101 may comprise various dopedregions (not individually illustrated) depending on design requirements(e.g., p-type substrate or n-type substrate). For example, the dopedregions may be doped with p-type dopants, such as boron or BF₂; n-typedopants, such as phosphorus or arsenic; and/or combinations thereof. Thedoped regions may be configured for an n-type GAA transistor, oralternatively configured for a p-type GAA transistor. In someembodiments, the substrate 101 may include trench isolation regions 104to isolate the various doped regions.

To help isolate the various doped region, trench isolation regions 104may be formed. In an embodiment the trench isolation regions may beformed by initially applying a first photo-sensitive layer (notillustrated in FIGS. 1A-1C) is formed on the substrate 101 and is thenpatterned, forming openings in the first photo-sensitive layer. In someembodiments, the lithography processes include forming the firstphoto-sensitive layer by spin-on coating, exposing the firstphoto-sensitive layer using an exposure energy, such as ultraviolet (UV)light, and developing the exposed first photo-sensitive layer to form apatterned first photo-sensitive layer (with the openings) using adeveloper. In another example, the lithography process includes spin-oncoating, soft baking, exposing, post-exposure baking, developing andhard baking. Alternatively, the lithography process to form thepatterned first photoresist layer may alternatively use othertechniques, such as e-beam lithography, maskless patterning or molecularprinting.

Once the first photo-sensitive layer has been formed, the exposedsubstrate 101 is etched through the first photo-sensitive layer to formtrenches (not separately illustrated in FIGS. 1A-1C) within thesubstrate 101. The first photo-sensitive layer is then removed. Next, acleaning may be performed to remove a native oxide of the substrate 101.The cleaning may be performed using diluted hydrofluoric (DHF) acid.

The trenches may then be filled with a dielectric material, followed bya chemical mechanical polish (CMP) to form the trench isolation regions104. The dielectric material may include silicon oxide. In someembodiments, other dielectric materials, such as silicon nitride,silicon oxynitride, fluoride-doped silicate glass (FSG), or a low-Kdielectric material, may also be used. In an embodiment, the dielectricmaterial may be formed using a high-density-plasma (HDP) CVD process,using silane (SiH₄) and oxygen (O₂) as reacting precursors. In otherembodiment, the dielectric material may be formed using asub-atmospheric CVD (SACVD) process or high aspect-ratio process (HARP),wherein process gases may comprise tetraethylorthosilicate (TEOS) andozone (O₃). In yet other embodiment, the dielectric material may beformed using a spin-on-dielectric (SOD) process, such as hydrogensilsesquioxane (HSQ) or methyl silsesquioxane (MSQ).

After formation of the trench isolation regions 104, a secondphoto-sensitive layer (also not illustrated in FIGS. 1A-1C) is formed onthe substrate 101 and is then patterned, forming openings in the secondphoto-sensitive layer to expose the substrate 101 and define areas forthe formation of the first nanowire 111 from the substrate 101. In anembodiment the exposed substrate 101 is etched to form the firstnanowire 111 from the substrate 101. The first nanowire 111 may beformed to have a first width W₁ of between about 1 nanometer and about100 nanometers, such as about 10 nanometers, and a first height H₁ ofbetween about 1 nanometer and about 1 micrometer, such as about 70nanometers.

Once the first nanowire 111 has been formed, the second photo-sensitivelayer is removed using a process such as ashing, whereby the temperatureof the second photo-sensitive layer is increased until the secondphoto-sensitive layer thermally decomposes. Next, a cleaning may beperformed to remove a native oxide of the substrate 101. The cleaningmay be performed using diluted hydrofluoric (DHF) acid.

In some embodiments, a first source/drain region 112 (indicated in FIGS.1B and 1C with a dashed line within the first nanowire 111) is formed bya first ion implantation process in the bottom portion of the firstnanowire 111. In some embodiments, a metal silicide may be formed on thesource region 212 (not shown).

The first source/drain region 112 includes an n-type dopant (such asphosphorous) when the GAA transistor is n-type or a p-type dopant (suchas boron) when the GAA transistor is p-type. In some embodiments, thefirst source/drain region 112 formed by the ion implantation is furtherannealed for activation by an annealing process. The annealing processmay be implemented right after the ion implantation may alternatively beimplemented after the formation of other doped features for collectiveactivation. In one embodiment, the annealing process includes rapidthermal annealing (RTA). In other embodiments, the annealing processalternatively includes laser annealing, spike annealing, millisecondanneal (MSA) or other suitable annealing technique.

Once the first source/drain region 112 has been formed, the firstcontact pad 103 is formed to provide electrical connection to the firstsource/drain region 112. In an embodiment the first contact pad 103 isformed of a conductive material such as aluminum, although othersuitable materials, such as copper, tungsten, or the like, mayalternatively be utilized. The first contact pad 103 may be formed usinga process such as CVD or PVD, although other suitable materials andmethods may alternatively be utilized. Once the material for the firstcontact pad 103 has been deposited, the material may be shaped into thefirst contact pad 103 using, e.g., one or more photolithographic maskingand etching processes. Looking at FIG. 1A, in an embodiment the firstcontact pad 103 is formed with a second width W₂ of between about 20nanometers and about 20 micrometers, such as about 485 nanometers, and asecond length L₂ of between about 9 nanometers and about 20 micrometers,such as about 360 nanometers.

Once the first contact pad 105 has been formed, a first isolation region106 is formed to isolate the substrate 101 and the subsequently formedgate electrode 105. In an embodiment the first isolation region 106 isformed over the first contact pad 103 and the substrate 101 and providesisolation function to and properly configures various features of theGAA transistor. In an embodiment the first isolation region 106 includesa dielectric material, such as silicon oxide. The first isolation region106 may alternatively include other suitable dielectric material, suchas silicon nitride, silicon oxynitride, carbon-doped silicon oxide,carbon-doped silicon nitride, or carbon-doped silicon oxynitride. Insome embodiments, the forming of the dielectric material layer includesdepositing a dielectric material using chemical vapor deposition (CVD),physical vapor deposition (PVD), or spin-on process, performing a CMPprocess to remove a portion of the dielectric material above the firstnanowire 111, and etching back the dielectric material to the desiredheight to help define the first source/drain region 112.

Once the first isolation region 106 has been formed, the gate dielectric102 and the gate electrode 105 surrounding a channel region 114 of thefirst nanowire 111 are formed. In an embodiment the gate electrode 105is formed to surround the channel region 114 of the first nanowire 111as well as to extend outwardly from the first nanowire 111 in order toallow for contact with the first gate contact 107.

In some embodiments, the gate dielectric 102 may include silicon oxide,silicon nitride, silicon oxynitride, or high-k dielectrics, such asmetal oxides. Examples of metal oxides that may be used as high-kdielectrics include oxides of Li, Be, Mg, Ca, Sr, Sc, Y, Zr, Hf, Al, La,Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and mixtures thereof.In the present embodiment, the gate dielectric 102 is a high-kdielectric layer with a thickness in the range of about 5 to 30angstroms. The gate dielectric 102 may be formed using a suitableprocess such as atomic layer deposition (ALD), chemical vapor deposition(CVD), physical vapor deposition (PVD), thermal oxidation, UV-ozoneoxidation, or combinations thereof. The gate dielectric 102 may furthercomprise an interfacial layer (not shown) to reduce damage between thegate dielectric 102 and the channel region 114 of the first nanowire111. The interfacial layer may comprise silicon oxide.

Once the gate dielectric 102 has been formed, the gate electrode 105 maybe formed. In an embodiment the gate electrode 105 may be formed byinitially forming a layer of metal (not separately illustrated in FIGS.1A-1C) over the gate dielectric 102. In some embodiments, the layer ofmetal may comprise a single layer or a multilayer structure. In thepresent embodiment, the layer of metal may include a metal such as Al,Cu, W, Ti, Ta, TiN, TiAl, TiAlN, TaN, NiSi, CoSi, other conductivematerials with a work function compatible with the substrate material,or combinations thereof. In the present embodiment, the gate electrodelayer comprises a uniform thickness in the range of about 1 nanometer toabout 20 nanometers. The layer of metal may be formed using a suitableprocess such as ALD, CVD, PVD, plating, or combinations thereof.

Once the layer of metal has been formed, the layer of metal may bepatterned to separate the gate electrode 105 illustrated in FIGS. 1A-1Cfrom other gate electrodes also formed from the layer of metal (notseparately illustrated in FIGS. 1A-1C) by being selectively etched. Inan embodiment the layer of metal may be patterned to form the gateelectrode 105 by initially applying a third photo-sensitive layer (notseparately illustrated in FIGS. 1A-1C) and then patterning the thirdphoto-sensitive layer to expose a portion of the layer of metal that isdesired to be removed and to cover a portion of the layer of metal thatis desired to remain.

After patterning the third photo-sensitive layer to expose the layer ofmetal, the layer of metal is etched using the third photo-sensitivelayer as a mask. In some embodiments, partially removing the exposedportion of the layer of metal is performed using a dry etch process at atemperature of about 10° C. to about 50° C., under a bias power of about100 W to about 1000 W and a pressure of about 1 mTorr to about 40 mTorr,using Cl₂, HBr, BCl₃, NF₃, N₂, CF₄ and CH₂F₂ as an etching gas. Once thelayer of metal has been patterned, the third photo-sensitive layer isremoved using a process such as, e.g., ashing.

Once the layer of metal has been patterned to separate the gateelectrode 105 from other gate electrodes, the layer of metal may also bepatterned to define the channel region 114 of the first nanowire 111. Inan embodiment the layer of metal may be patterned in this direction byinitially forming a second isolation region 108 over the layer of metal.In an embodiment the second isolation region 108 includes a dielectricmaterial, such as silicon oxide in the present example. The secondisolation region 108 may alternatively include other suitable dielectricmaterial, such as silicon nitride, silicon oxynitride, carbon-dopedsilicon oxide, carbon-doped silicon nitride, or carbon-doped siliconoxynitride. In some embodiments, the forming of the dielectric materiallayer includes depositing a dielectric material using CVD, PVD, orspin-on process, performing a CMP process to remove a portion of thedielectric material above the first nanowire 111, and etching back thedielectric material to a desired height to help define the channelregion 114.

Once the second isolation feature 108 has been formed to help define thechannel region 114, the second isolation region 108 may be used as amask to help remove exposed portions of the layer of metal from over thefirst nanowire 111 and form the gate electrode 105 surrounding thechannel region 114 of the first nanowire 111. In some embodiments,partially removing the exposed portion of the remaining layer of metalis performed using a dry etch process at a temperature of about 10° C.to about 50° C., under a bias power of about 100 W to about 1000 W and apressure of about 1 mTorr to about 40 mTorr, using Cl₂, HBr, BCl₃, NF₃,N₂, CF₄ and CH₂F₂ as an etching gas. In an embodiment the gate electrode105 may be formed to have a third width W₃ of between about 20nanometers and about 20 micrometers, such as about 340 nanometers and athird length L₃ of between about 9 nanometers and about 20 micrometers,such as about 315 nanometers.

Once the channel region 114 has been defined by the gate electrode 105,a second source/drain region 116 may be formed in a portion of the firstnanowire 111 uncovered by the gate electrode 105. In an embodiment, thesecond source/drain region 116 is formed by a second ion implantationprocess in the upper portion of the first nanowire 111. The secondsource/drain region 116 includes an n-type dopant (such as phosphorous)when the GAA transistor is n-type or a p-type dopant (such as boron)when the GAA transistor is p-type. In some embodiments, the secondsource/drain region 116 formed by the ion implantation is furtherannealed for activation by an annealing process. The annealing processis implemented after the ion implantation or is alternativelyimplemented after the formation of other doped features for collectiveactivation. In one embodiment, the annealing process includes rapidthermal annealing (RTA). In other embodiments, the annealing processalternatively includes laser annealing, spike annealing, millisecondanneal (MSA) or other suitable annealing technique.

Once the gate electrode 105 and the second source/drain region 116 havebeen formed, a third isolation region 110 may be formed to isolate thesecond source/drain region 116 within the first nanowire 111. In anembodiment the third isolation region 110 includes a dielectricmaterial, such as silicon oxide. The third isolation region 110 mayalternatively include other suitable dielectric material, such assilicon nitride, silicon oxynitride, carbon-doped silicon oxide,carbon-doped silicon nitride, or carbon-doped silicon oxynitride. Insome embodiments, the forming of the dielectric material includesdepositing a dielectric material using, e.g., CVD, PVD, or a spin-onprocess, and then performing a CMP process to remove a portion of thedielectric material above the first nanowire 111.

Once the third isolation region 110 has been formed, the second contactpad 113 may be formed in electrical connection with the first nanowire111. In an embodiment the second contact pad 113 is formed in order toprovide electrical connection between the second source/drain region 116within the first nanowire 111 and, e.g. ,the first top contact 115. Inan embodiment the second contact pad 113 is formed of a conductivematerial such as aluminum, although other suitable materials, such ascopper, tungsten, or the like, may alternatively be utilized. The secondcontact pad 113 may be formed using a process such as CVD or PVD,although other suitable materials and methods may alternatively beutilized. Once the material for the second contact pad 113 has beendeposited, the material may be shaped into the second contact pad 113using, e.g., a photolithographic masking and etching process. Looking atFIG. 1A, in an embodiment the second contact pad 113 is formed with afourth width W₄ of between about 9 nanometers and about 20 micrometers,such as about 280 nanometers, and a fourth length L₄ of between about 9nanometers and about 20 micrometers, such as about 260 nanometers.

After the second contact pad 113 has been formed, a fourth isolationregion 117 may be formed to help isolate the second contact pad 113. Inan embodiment the fourth isolation region 117 includes a dielectricmaterial, such as silicon oxide in the present example. The fourthisolation region 117 may alternatively include other suitable dielectricmaterial, such as silicon nitride, silicon oxynitride, carbon-dopedsilicon oxide, carbon-doped silicon nitride, or carbon-doped siliconoxynitride. In some embodiments, the forming of the dielectric materiallayer includes depositing a dielectric material using CVD, PVD, or aspin-on process. If desired, a CMP process may be utilized to planarizethe fourth isolation region 117.

Once the VGAA transistor 100 has been formed, the first bottom contact109, the first gate contact 107, and the first top contact 115 may beformed in order to electrically connect the first source/drain region112, the second source/drain region 116, and the gate electrode 105. Inan embodiment the first bottom contact 109, the first gate contact 107,and the first top contact 115 may be formed either together orseparately by initially applying a fifth photo-sensitive material,patterning the fifth photo-sensitive material, and then removingportions of the fourth isolation region 117, the third isolation region110, the second isolation region 108, and the first isolation region 106to form openings and to expose portions of the second contact pad 113,the gate electrode 105, and the first contact pad 103.

Looking at FIG. 1A, in an embodiment the first bottom contact 109 may beformed to a fifth width W₅ of between about 1 nanometer and about 1micrometer, such as about 40 nanometers, and a fifth length L₅ ofbetween about 1 nanometer and about 20 micrometers, such as about 216nanometers. Additionally, the first top contact 115 may be formed to asixth width W₆ of between about 1 nanometer and about 20 micrometers,such as about 72 nanometers, and a sixth length L₆ of between about 1nanometer and about 20 micrometers, such as about 26 nanometers. Thefirst gate contact 107 may be formed to a seventh width W₇ of betweenabout 1 nanometer and about 20 micrometers, such as about 50 nanometersand a seventh length L₇ of between about 1 nanometer and about 20micrometers, such as about 50 nanometers.

Once the openings have been formed, the openings may be filled with aconductive material. In an embodiment the conductive material may becopper, although any suitable material may be used, and may be formed byinitially forming a seed layer within the openings and then using aprocess such as plating in order to fill or overfill the openings withthe conductive material. Once filled, any excess conductive materiallocated outside of the openings may be removed using, e.g., a chemicalmechanical polishing process.

By utilizing the first contact pad 103 and the second contact pad 113,the asymmetrical nature of the source/drain regions that can occur inthe manufacturing process may be reduced or eliminated. By minimizingthe variations between the source/drain regions, a more consistentdevice with better control may be manufactured.

FIGS. 2A-2D illustrate various embodiments which utilize a differentnumber and placement of nanowires (e.g., the first nanowire 111, asecond nanowire 201, and a third nanowire 203) in accordance withvarious embodiments. Looking first at FIG. 2A, FIG. 2A illustrates anembodiment in which, instead of the first nanowire 111, the secondnanowire 201 and the third nanowire 203 are utilized. In an embodimentthe second nanowire 201 and the third nanowire 203 are utilized withinthe VGAA transistor 100. In one embodiment the second nanowire 201 andthe third nanowire 203 may be formed to similar dimensions and usingsimilar process as the first nanowire 111 (described above with respectto FIGS. 1A-1C). However, the second nanowire 201 and the third nanowire203 may alternatively be formed to different dimensions or usingdifferent process.

In an embodiment the second nanowire 201 and the third nanowire 203 arelocated such that they are not overlaid by the first top contact 115.For example, and as illustrated in FIG. 2A, the second nanowire 201 andthe third nanowire 203 are located on opposing sides of the first topcontact 115, and may be separated from each other by a first distance D₁of less than about 20 micrometers, such as about 96 nanometers. However,any suitable distance may alternatively be utilized.

FIG. 2B illustrates another embodiment in which the first nanowire 111is used in conjunction with the second nanowire 201 and the thirdnanowire 203. In this embodiment the first nanowire 111 is locatedbeneath the first top contact 115 while the second nanowire 201 and thethird nanowire 203 are located as described above with respect to FIG.2A.

FIG. 2C illustrates another embodiment in which the second nanowire 201and the third nanowire 203 are formed so as to be located at leastpartially beneath the first top contact 115. In this embodiment thesecond nanowire 201 and the third nanowire 203 may be arranged along aline that extends between the first gate contact 107 and the firstbottom contact 109 (in the top down view).

FIG. 2D illustrates another embodiment in which the second nanowire 201and the third nanowire 203 are arranged as described in FIG. 2C. In thisembodiment, however, the first nanowire 111 is additionally included andis located beneath the first top contact 115. As illustrated, the firstnanowire 111, the second nanowire 201, and the third nanowire 203 areall in a line with the first gate contact 107 and the first bottomcontact 109.

FIGS. 3A-3D illustrate further embodiments in which the first nanowire111, the second nanowire 201, and the third nanowire 203 are arranged inlines that are not parallel with the borders of the VGAA transistor 100.FIG. 3A illustrates an embodiment in which the positions of the secondnanowire 201 and the third nanowire are rotated around the first topcontact 115 such that the second nanowire 201 and the third nanowire 203are at separate distances from the first gate contact 107. In theembodiment illustrated in FIG. 3A, the third nanowire 203 is locatedcloser to the first gate contact 107 than the second nanowire 201.

FIG. 3B illustrates another embodiment similar to the embodimentillustrated in FIG. 3A. In this embodiment, however, the locations ofthe second nanowire 201 and the third nanowire 203 are rotated in anopposite direction than the embodiment discussed above with respect toFIG. 3A. Accordingly, in this embodiment the second nanowire 201 islocated closer to the first gate contact 107 than the third nanowire203.

FIGS. 3C and 3D illustrate further embodiments which the positions ofthe second nanowire 201 and the third nanowire 203 have been rotated asdescribed above with respect to FIGS. 3A and 3B, respectively. In theseembodiments, however, the second nanowire 201 and the third nanowire 203are utilized in conjunction with the first nanowire 111, which islocated as centered beneath the first top contact 115 as described abovewith respect to FIGS. 1A-1C.

FIG. 4 illustrates another embodiment in which an array of nanowires 401is utilized. In this embodiment, instead of using one, two, or threenanowires (as described above with respect to FIGS. 2A-3D), the array ofnanowires 401 may comprise a larger number of nanowires of between about1 and about 1000000, such as about 96 nanowires. In the embodimentillustrated in FIG. 4, the array of nanowires 401 is arranged such thatthe individual nanowires are located in evenly spaced rows and columns.In an embodiment there are between about 1 row and about 1000 rows, suchas about 12 rows and between about 1 column and about 1000 columns, suchas about 8 columns.

In this embodiment the rows and columns may be evenly spaced apart fromeach other. For example, in an embodiment in which each one individualnanowire within the array of nanowires 401 has a diameter of betweenabout 1 nanometer and about 100 nanometer, such as about 10 nanometer,the individual rows within the array of nanowires 401 may have a firstpitch P₁ of less than about 20 micrometers, such as about 96 nanometers.Additionally, the individual columns within the array of nanowires 401may have a second pitch P₂ of less than about 20 micrometers, such asabout 96 nanometers.

FIG. 5 illustrates another embodiment that utilizes the array ofnanowires 401. In this embodiment, however, instead of the plurality ofnanowires being in evenly spaced rows and columns, the array ofnanowires are arranged in rows and columns that are offset from eachother. For example, in an embodiment in which the individual nanowireswithin the array of nanowires 401 have a diameter of about 10nanometers, the rows may have a third pitch P₃ of less than about 20micrometers, such as about 96 nanometers. However, adjacent rows may beoffset from each other by a second distance D₂ of less than about 20micrometers, such as about 96 nanometers.

By utilizing two or more nanowires, the overall VGAA transistor 100 canhandle a larger current with less detrimental effects than the VGAAtransistor 100 with only a single nanowire. As such, the VGAA transistor100 can be utilized for a wide variety of applications. Additionally, byrotating the positions of the second nanowire 201 and the third nanowire203, the benefits of using multiple nanowires may be achieved while alsoreducing the area needed for the placement of the multiple nanowires.

FIGS. 6A-6F illustrate further embodiments which utilize one or morebottom contacts (e.g., the first bottom contact 109, a second bottomcontact 601, and a third bottom contact 603). Looking first at FIG. 6A,FIG. 6A illustrates the second bottom contact 601, instead of beinglocated in line with the first top contact 115 and the gate electrode105 as the first bottom contact 109 is in FIGS. 1A-1C, is located alonga line that is at a right angle from a line that extends from the firsttop contact 115 and the first gate contact 107. In this embodiment thesecond bottom contact 601 may have an eight width W₈ of between about 1nanometer and about 20 micrometers, such as about 240 nanometers, and aeighth length L₈ of between about 1 nanometer and about 20 micrometers,such as about 40 nanometers. The second bottom contact 601 may be formedusing similar materials and similar processes as the first bottomcontact 109 (illustrated and discussed above with respect to FIGS.1A-1C).

FIG. 6B illustrates another embodiment in which the second bottomcontact 601 is utilized in conjunction with the third bottom contact603. In an embodiment the third bottom contact 603 is similar to thesecond bottom contact 601, but is located on an opposite side (in thetop down view of FIG. 6B) of the first nanowire 111 than the secondbottom contact 601.

FIG. 6C illustrates an embodiment in which the second bottom contact 601is utilized in conjunction with the first bottom contact 109 and withoutthe third bottom contact 603. In this embodiment the first bottomcontact 109 is located as described above with respect to FIGS. 1A-1C,and the second bottom contact 601 is located as described above withrespect to FIG. 6A.

FIG. 6D illustrates an embodiment in which the first bottom contact 109,the second bottom contact 601, and the third bottom contact 603 are allutilized together. In this embodiment the first bottom contact 109 islocated as described above with respect to FIGS. 1A-1C, the secondbottom contact 601 is located as described above with respect to FIG.6A, and the third bottom contact 603 is located as described above withrespect to FIG. 6B.

FIG. 6E illustrates an embodiment in which, instead of using the firstbottom contact 109, the second bottom contact 601, and the third bottomcontact 603 as separate structures, the first bottom contact 109, thesecond bottom contact 601, and the third bottom contact 603 are mergedinto a single U-shaped bottom contact 605. In this embodiment theU-shaped bottom contact 605 may have a first thickness T₁ of betweenabout 1 nanometer and about 20 micrometers, such as about 40 nanometers.Additionally, the U-shaped bottom contact 605 may have a ninth width W₉of between about 1 nanometer and about 20 micrometers, such as about 240nanometers, and a ninth length L₉ of between about 3 nanometers, andabout 20 micrometers, such as about 296 nanometers.

FIG. 6F illustrates an embodiment in which the, instead of using thefirst bottom contact 109, the second bottom contact 601, and the thirdbottom contact 603 separately, the first bottom contact 109 and thesecond bottom contact 601 are merged into a single L-shaped bottomcontact 607. The single L-shaped bottom contact 607 may have the firstthickness T₁, the ninth width W₉ and the ninth length L₉, although withonly two legs instead of three.

FIGS. 7A-7E illustrate embodiments which utilize one or more topcontacts (e.g., the first top contact 115, a second top contact 701, athird top contact 703, a fourth top contact 705, or a fifth top contact710). Looking first at FIG. 7A, FIG. 7A illustrates an embodiment whichuses the first top contact 115 along with the second top contact 701,wherein both the first top contact 115 and the second top contact 701have a longitudinal axis that is parallel with a line extending betweenthe first gate contact 107 and the first bottom contact 109. In thisembodiment the first top contact 115 and the second top contact 701 mayeach have a tenth length L₁₀ of between about 1 nanometer and about 10micrometers, such as about 20 nanometers, and a tenth width W₁₀ ofbetween about 1 nanometer and about 20 micrometers, such as about 72nanometers. Additionally, the first top contact 115 and the second topcontact 701 may be spaced from each other a third distance D₃ of lessthan about 10 micrometers, such as about 60 nanometers.

FIG. 7B illustrates a plurality of top contacts, such as the first topcontact 115, the second top contact 701, the third top contact 703, thefourth top contact 705, and the fifth top contact 710. Each of thesecontacts may have similar dimensions, such as the tenth width W₁₀ andthe tenth length L₁₀, and may be spaced apart from each other by thethird distance D₃.

FIG. 7C illustrates an embodiment in which the first top contact 115,instead of having a longitudinal axis that is parallel to a lineextending between the first gate contact 107 and the first bottomcontact 109, has a longitudinal axis that is perpendicular with the lineextending between the first gate contact 107 and the first bottomcontact 109. In this embodiment the first top contact 115 may have aneleventh width W₁₁ of between about 1 nanometer and about 20micrometers, such as about 20 nanometers, and an eleventh length L₁₁ ofbetween about 1 nanometer and about 20 micrometers, such as about 40nanometers.

FIG. 7D illustrates an embodiment in which the first top contact 115 isoriented as described above with respect to FIG. 7C, and in which thesecond top contact 701 is additionally utilized. In this embodiment thesecond top contact 701 is oriented similar to the first top contact 115(e.g., having a longitudinal axis perpendicular to the line extendingbetween the first gate contact 107 and the first bottom contact 109).Additionally, the first top contact 115 and the second top contact 701may be separated from each other by a fourth distance D₄ of less thanabout 20 micrometers, such as about 40 nanometers.

FIG. 7E illustrates an embodiment in which the third top contact 703 isutilized along with the second top contact 701 and the first top contact115 wherein the third top contact 703 is oriented similar to the secondtop contact 701 (e.g., having a longitudinal axis parallel with alongitudinal axis of the first top contact 115). In this embodiment thefirst top contact 115, the second top contact 701, and the third topcontact 703 are formed with a twelfth width W₁₂ of between about 1nanometer and about 10 micrometers, such as about 20 nanometers, and atwelfth length L₁₂ of between about 1 nanometer and about 10micrometers, such as about 240 nanometers. Additionally, the first topcontact 115, the second top contact 701, and the third top contact 703may be separated from each other by a fifth distance D₅ of less thanabout 20 micrometers, such as about 20 nanometers.

FIGS. 8A-8C illustrate embodiments that utilize a single top contactwith differing shapes. FIG. 8A illustrates an embodiment in which asingle L-shaped top contact 707 is utilized. In an embodiment the singleL-shaped top contact 707 has a second thickness T₂ of between about 1nanometer and about 20 micrometers, such as about 40 nanometers.Additionally, the single L-shaped top contact 707 may have a thirteenthwidth W₁₃ of between about 1 nanometer and about 20 micrometers, such asabout 240 nanometers, and a thirteenth length L₁₃ of between about 1nanometer and about 20 micrometers, such as about 240 nanometers.

FIG. 8B illustrates an embodiment in which a single U-shaped top contact709 is utilized instead of the single L-shaped top contact 707 describedabove with respect to FIG. 8A. In an embodiment the single U-shapedcontact 709 has the second thickness T₂, the thirteenth width W₁₃, andthe thirteenth length L₁₃, although any suitable dimensions mayalternatively be utilized.

FIG. 8C illustrates another embodiment which utilizes a single, squaredshaped top contact 711 which, in the top down view of FIG. 8C, surroundsthe first nanowire 111. In this embodiment the single, square shapedcontact 711 has the second thickness T₂, the thirteenth width W₁₃, andthe thirteenth length L₁₃, but has four sides instead of three sides (asin the embodiment illustrated in FIG. 8B) or two sides (as in theembodiments illustrated in FIG. 8A).

FIG. 9A illustrates an embodiment in which one or more gate contacts(e.g., the first gate contact 107, a second gate contact 901, or a thirdgate contact 903) is utilized. In the embodiment illustrated in FIG. 9A,the second gate contact 901 may be similar to the first gate contact 107(described above with respect to FIGS. 1A-1C). The second gate contact901, however, is not aligned with the first top contact 115 and thefirst bottom contact 109 (as the first gate contact 107 is aligned inFIGS. 1A-1C), but is instead aligned along a line that is perpendicularto a line that runs through the first top contact 115 and the firstbottom contact 109.

Additionally, in this embodiment the gate electrode 105 may be sized toaccommodate the changed position of the second gate contact 901. In anembodiment the gate electrode 105 has a fourteenth width W₁₄ of betweenabout 1 nanometer and about 20 micrometers, such as about 480nanometers, and a fourteenth length L₁₄ of between about 1 nanometer andabout 20 micrometers, such as about 450 nanometers. However, anysuitable size may alternatively be utilized.

FIG. 9B illustrates an embodiment in which a third gate contact 903 isutilized. In an embodiment the third gate contact 903 may be similar tothe second gate contact 901, although located on an opposite side of thefirst nanowire 111 than the second gate contact 901. In this embodimentthe gate electrode 105 may have the fourteenth width W₁₄ and thefourteenth length W₁₄, although extending in an opposite direction thanthe embodiment illustrated in FIG. 9A.

FIG. 9C illustrates an embodiment which utilizes the second gate contact901 and the third gate contact 903. In an embodiment the second gatecontact 901 is located as described above with respect to FIG. 9A andthe third gate contact 903 is located as described above with respect toFIG. 9B. Additionally, in this embodiment the gate electrode 105 has afifteenth width W₁₅ of between about 1 nanometer and about 20micrometers, such as about 480 nanometers, and a fifteenth length L₁₅ ofbetween about 3 nanometers and about 20 micrometers, such as about 600nanometers.

FIG. 9D illustrates another embodiment in which the first gate contact107 is utilized with the second gate contact 901. In this embodiment thefirst gate contact 107 is located as described above with respect toFIGS. 1A-1C, and the second gate contact 901 is located as describedabove with respect to FIG. 9A. Additionally, in this embodiment the gateelectrode 105 has a sixteenth width W₁₆ of between about 2 nanometersand about 20 micrometers, such as about 600 nanometers, and a sixteenthlength L₁₆ of between about 2 nanometers and about 20 micrometers, suchas about 600 nanometers.

FIG. 9E illustrates an embodiment in which the first gate contact 107 isutilized with the third gate contact 903. In this embodiment the firstgate contact 107 is located as described above with respect to FIGS.1A-1C, and the third gate contact 903 is located as described above withrespect to FIG. 9B. Additionally, in this embodiment the gate electrode105 has the sixteenth width W₁₆ and the sixteenth length L₁₆.

FIG. 9F illustrates an embodiment in which the first gate contact 107 isutilized with the second gate contact 901 and the third gate contact903. In this embodiment the first gate contact 107 is located asdescribed above with respect to FIGS. 1A-1C, the second gate contact 901is located as described above with respect to FIG. 9A, and the thirdgate contact 903 is located as described above with respect to FIG. 9B.Additionally, in this embodiment the gate electrode 105 has aseventeenth width W₁₇ of between about 2 nanometers and about 20micrometers, such as about 480 nanometers, and a seventeenth length L₁₇of between about 3 nanometers and about 20 micrometers, such as about600 nanometers.

Additionally, as one of ordinary skill in the art will understand, theembodiments described herein are not intended to be isolated from eachother. Rather, any embodiment may be utilized with any other embodimentdescribed herein. For example, the embodiments illustrated herein withmultiple nanowires may be utilized with the embodiments illustratedherein with multiple bottom contacts and multiple top contacts. Anysuitable combination may be utilized, and all such combinations arefully intended to be included within the scope of the embodiments.

By utilizing the above described embodiments, the VGAA transistor 100may be formed to suit a wide variety of different applications whilekeeping variations within the VGAA transistor 100 to a minimum. As such,by reducing variations, the output may be better controlled, and anoverall better product may be manufactured.

In accordance with an embodiment, a semiconductor device comprising afirst nanowire over a substrate, the first nanowire being perpendicularto the substrate and comprising a first source/drain region, a channelregion over the first source/drain region, and a second source/drainregion over the channel region is provided. A first contact pad is atleast partially surrounding the first source/drain region. A gateelectrode is at least partially surrounding the channel region. A secondcontact pad is in electrical connection with the second source/drainregion.

In accordance with another embodiment, a semiconductor device comprisinga first contact pad on a substrate and a second contact pad over thefirst contact pad is provided. A first nanowire extends between thefirst contact pad and the second contact pad and a gate electrode issurrounding a channel region of the first nanowire.

In accordance with yet another embodiment a method of manufacturing asemiconductor device comprising forming a first nanowire from asubstrate is provided. A first contact pad is formed adjacent to a lowerportion of the first nanowire. A gate electrode is formed adjacent to amiddle portion of the first nanowire, and a second contact pad is formedadjacent to an upper portion of the first nanowire.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A semiconductor device comprising: a first nanowire over a substrate, the first nanowire being perpendicular to the substrate and comprising a first source/drain region, a channel region over the first source/drain region, and a second source/drain region over the channel region; a first contact pad at least partially surrounding the first source/drain region; a gate electrode at least partially surrounding the channel region; and a second contact pad in electrical connection with the second source/drain region.
 2. The semiconductor device of claim 1, further comprising a second nanowire, wherein the second nanowire comprises: a third source/drain region, wherein the first contact pad is at least partially surrounding the third source/drain region; and a fourth source/drain region, wherein the second contact pad is at least partially surrounding the fourth source/drain region.
 3. The semiconductor device of claim 2, further comprising a third nanowire, wherein the third nanowire comprises: a fifth source/drain region, wherein the first contact pad is at least partially surrounding the fifth source/drain region; and a sixth source/drain region, wherein the second contact pad is at least partially surrounding the sixth source/drain region.
 4. The semiconductor device of claim 1, further comprising: a first bottom contact in electrical connection with the first contact pad; a first top contact in electrical connection with the second contact pad; and a gate contact in electrical connection with the gate electrode.
 5. The semiconductor device of claim 4, further comprising a second top contact in electrical connection with the second contact pad, wherein the second top contact is laterally separated from the first top contact.
 6. The semiconductor device of claim 4, wherein the first top contact is an L-shaped contact.
 7. The semiconductor device of claim 4, wherein the first top contact is a U-shaped contact.
 8. The semiconductor device of claim 4, wherein the first top contact is a square shaped contact.
 9. A semiconductor device comprising: a first contact pad on a substrate; a second contact pad over the first contact pad; a first nanowire extending between the first contact pad and the second contact pad; and a gate electrode surrounding a channel region of the first nanowire.
 10. The semiconductor device of claim 9, wherein the first nanowire is part of an array of nanowires, wherein the array of nanowires has evenly spaced columns and rows.
 11. The semiconductor device of claim 9, wherein the first nanowire is part of an array of nanowires, wherein the array of nanowires has columns that are offset from each other.
 12. The semiconductor device of claim 9, further comprising: a first contact in electrical connection with the first contact pad; and a second contact in electrical connection with the first contact pad, the second contact being laterally separated from the first contact.
 13. The semiconductor device of claim 12, further comprising a third contact in electrical connection with the first contact pad, the third contact being laterally separated from the first contact and the second contact.
 14. The semiconductor device of claim 9, further comprising: a first gate contact in electrical connection with the gate electrode; and a second gate contact in electrical connection with the gate electrode, wherein the second gate contact is laterally separated from the first gate contact.
 15. The semiconductor device of claim 14, further comprising a third gate contact in electrical connection with the gate electrode, wherein the third gate contact is laterally separated from the first gate contact and the second gate contact.
 16. A method of manufacturing a semiconductor device, the method comprising: forming a first nanowire from a substrate; forming a first contact pad adjacent to a lower portion of the first nanowire; forming a gate electrode adjacent to a middle portion of the first nanowire; and forming a second contact pad adjacent to an upper portion of the first nanowire.
 17. The method of claim 16, further comprising forming a second nanowire from the substrate, wherein the forming the second contact pad further comprises forming the second contact pad adjacent to the second nanowire.
 18. The method of claim 17, further comprising forming an array of nanowires.
 19. The method of claim 16, further comprising forming a first contact to the first contact pad, wherein the first contact is an L-shaped contact.
 20. The method of claim 16, further comprising forming a first contact to the first contact pad, wherein the first contact is a U-shaped contact. 